Hikikomori is a term used in Japan to describe people who act as recluses and rarely leave their houses, preferring to spend their days and nights usually on the internet, especially on Japan's 2ch. Since such people hold no job, they state their occupation as 'hikikomori', which literally means 'home security guard' as a means to sugar-coat their unemployment, and generally nerd, status.

I'm not going to go out at all this summer- I'm going to stay home and be hikikomori.

Someone who has withdrawn from all real-life social interaction. A hikikomori rarely leaves their home, and has no friends or family with whom they interact. A hikikomori is NOT always an otaku, nerd, gamer, etc, though they can be.

A Person who dwells in their home, and collects money from somewhere else, and is sent to his/her house, and he/she almost never leaves his/her own house, ussally the money is from welfare or a family member. (sometimes an online game/job)

Was used and written in an Anime called: Welcome to the N.H.K.

See: Neet

Me: I don't want to go swimming with you guys, I would rather sit at home, with my freaking laptop all summer like a hikikomori.
Others: What the F dude....